i think that this was a good starting point for your story. needless to say, i am intrigued. one thing i'd like to mention that has helped me out so far. once you're done writing it, read it! this helps out a lot. it helps to catch mistakes and you're looking at the story from our (the reader's) perspective.
one more thing, since you are writing about batman beyond, i thought you might be interested in checking out another BB fanfic that has been written on these boards. it's called Legacys. you should check it out! it's a really good story! i should know, i wrote it!
keep up the good work! we're a nice bunch of people. if you need help with something, don't hesitate to ask!